[Elecraft] T1 tuner issue: try shorting the feedline, working against ground

[Ron D'Eau Claire]

A variation on the idea proposed by Wayne is to add an inductor or capacitor
in series with the center wire in the feeder. That will change the impedance
presented to the tuner. You may need to experiment a bit to find a value
that the ATU can match - as indicated by a low SWR - but you won't have to
fiddle with a separate ground system. You whatever you have handy - a 20 to
50 pf cap or a dozen turns of hook-up wire around a 35 mm plastic film
container. You aren't looking for any exact value, just enough reactance to
move the impedance into a range the T1 can match. 

Ron AC7AC  



-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of wayne burdick
Sent: Tuesday, October 25, 2005 4:32 PM
Cc: Elecraft Reflector; QRP-L; Kurt Loken
Subject: [Elecraft] T1 tuner issue: try shorting the feedline,working
against ground


Kurt,

The impedance of your 40 m dipole on 20 m is probably sky-high; 2.5:1 
may be the best you can hope for. This probably won't hurt the rig, and 
the power loss due to the high SWR is probably less than a dB assuming 
the rig doesn't roll back power (or clip the voltage at the collector 
of its PA).

Another thing you can try is to short the coax center connector to its 
shield. This is an old trick for extending the matching range of an 
antenna. Connect this to the T1's hot lead, then connect the T1's 
ground to a ground counterpoise. The impedance will likely be very 
different, giving the ATU a chance to match it. It will be slightly 
noisier than a dipole, and the directivity will change, but you may not 
mind.

73,
Wayne
N6KR


---

http://www.elecraft.com

_______________________________________________
Elecraft mailing list
Post to: Elecraft at mailman.qth.net
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft    

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com